<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .box {
        width: 200px;
        height: 200px;
        border: 2px solid black;
    }

    .big {
        width: 500px;
        height: 500px;
    }

    .pink {
        background-color: pink;
    }
</style>
<body>
<div id="app">
    <div class="box" :class="['big','pink']"></div>
    <div class="box" :class="{'big':true,'pink':false}"></div>
</div>

</body>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    const app = new Vue({
        el: '#app',
        data: {}
    })


</script>
</html>